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Investigate  the relationship between the amount of force applied and the mass of the object to the amount of change in the object’s motion.  (S8FE-Ia-15 )

After going through this module, you are expected to:

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When a  jeepney  starts moving, it speeds up. When a  jeepney  nears a stop sign, it slows down. The  jeepney  is covering different displacements at equal time intervals and hence it is not moving at a uniform velocity. In other words, the  jeepney  is accelerating.

Most of the motions we come across in our daily life are non-uniform and the primary cause of changes in motion is FORCE.

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The distance covered by a moving object from one place to another.

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The speed that an object gains as it starts to move.

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The rate of change of velocity of an object per unit time

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- The  push  or  pull  done to an object.

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Figure 1. If someone pushes the ball, it will move or roll across the surface of the table (Figure 1a). And when it is again pushed in the direction of its motion, it moves farther and even faster (Figure 1b). But when you push it on the other side instead, opposite to the direction of its motion, the ball may slow down and eventually stop (Figure 1c). Lastly, when you push it in a direction different from its original direction of motion, the ball also changes its direction (Figure 1d).

Force, therefore, can make objects move, move faster, stop, or change their direction of motion.

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Force is described  in terms of  the following properties:

Magnitude Direction Point of Application Line of Action

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NEWTON (N) - for Meter-Kilogram-Second (MKS)system

DYNE ( dyn ) - for Centimeter-Gram-Second (CGS)system

POUNDS ( lbs ) - for Foot-Pound-Second (CGS)system

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An object may be acted upon by several forces. For example, an object may be pushed and pulled in different directions at the same time. To identify which of these forces would be able to cause change in the motion of the object, it is important to identify all the forces acting on it.

Balanced forces do not cause a change in motion. When balanced forces act on an object at rest, the object will not move.

Unbalanced forces are not equal and in opposite direction.

Forces that are equal in  magnitude  but  opposite in direction  are called  balanced forces.  Forces that are  not equal  and in  opposite direction  are  unbalanced forces .

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Net force  or  resultant force  is the sum of all forces acting on an object.

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COMBINING FORCES:   Balanced or Unbalance Forced

F net  = F a  + F b          =  (+) 10 units  +   (-) 5 units           = 5 units

I f a  boy and  a  girl pull the heavy  box  at the same time in opposite directions with 10 units and 5 units of force respectively,  what will be the net force on the object? Will the object move? To what direction will it move?

FORCES

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